Interaction of casein kinase 1 delta (CK1δ) with post-Golgi structures, microtubules and the spindle apparatus

Members of the casein kinase 1 family of serine/threonine kinases are highly conserved from yeast to mammals and seem to play an important role in vesicular trafficking, DNA repair, cell cycle progression and cytokinesis. We here report that in interphase cells of various mammalian species casein kinase I delta (CK1 delta) specifically interacts with the trans Golgi network and cytoplasmic, granular particles that associate with microtubules. Furthermore, at mitosis CK1 delta is recruited to the spindle apparatus and the centrosomes in cells, which have been exposed to DNA-damaging agents Like etoposide or gamma-irradiation, In addition, determination of the affinity of CK1 delta to different tubulin isoforms in immunoprecipitation-Western anat sis revealed a dramatically enhanced complex formation between CK1 delta and tubulins from mitotic extracts after introducing DNA damage. The high affinity of CK1 delta to the spindle apparatus in DNA-damaged cells and its ability to phosphorylate several microtubule-associated proteins points to a regulatory. role of CK1 delta at mitosis.